1. Field of Invention
The present invention relates to processing of image data. More particularly, the present invention relates to a method and apparatus for spatially filtering an image, wherein the filter size is adjusted based on which portion of the image is being processed.
2. Background Information
Historically, reconnaissance information has provided important information used in planning military operations. For example, prior to the advent of photography, scouts would be sent out to collect information regarding natural resources such as lakes and rivers, enemy troop information and the like. With the advent of photography, these scouts would provide reconnaissance information by capturing a scene of enemy installations, battlefields, and the like, using photographs. As technology advances, new methods are provided for collecting reconnaissance information. For example, it is quite common today to have reconnaissance planes, manned or remotely controlled, or satellites capture a scene for reconnaissance purposes. In addition to conventional photographic techniques, a scene can be captured using infrared detectors and the like.
Typically scenes captured by reconnaissance techniques have been analyzed by humans in order to determine the content of the captured scene. For example, a human would analyze a photograph to determine the location of bodies of water, the location of enemy troops and the location of man-made objects such as buildings and lines of communication. The human who analyzed the photograph would then have to relay the determined information to people in the field, for example, to an airplane pilot in order to identify targets. However, using humans to analyze photographs is very labor intensive. Further, there can be a considerable delay between the time when a scene is captured and the time in which the information in the captured scene is relayed to persons in the field.
Moreover, a person who receives a captured scene may not have the time to analyze it. For example, in a single seat aircraft scenes captured by sensors on the aircraft can be provided directly to the pilot. However, in addition to analyzing a scene, the pilot also has to fly the aircraft.
Accordingly, it would be desirable to automate the analysis of images. Further, it would be desirable to provide mechanisms for determining whether the automated analysis is producing accurate results.